Apparatus and method for vaporizing carbon dioxide



Jan. 23, 1951 H. v. WILLIAMSON ET AL 2,539,291

I APPARATUS AND METHOD FOR VAPORIZING CARBON DIOXIDE Filed June 8, 1948 5 Sheets-Sheet l mow e v, L

Jan. 23, 1951 H. v. WILLIAMSON ETAL 2,539,291

APPARATUS AND METHOD FOR VAPORIZING CARBON DIOXIDE Filed June 8, 1948 5 Sheets-Sheet 2 W MM Jan- 23, 1951 H. v. WILLIAMSON ETAL 2,539,291

APPARATUS AND METHOD FIOR VAPORIZING CARBON DIOXIDE Filed June 8, 1948 3 Sheets-Sheet 5 Patented Jan. 23, 1951 APPARATUS AND MECHD FOB, VAPOREZENG vCARBON DIXIDE Hilding V. Williamson and .l ames C. Hessen, Chicago, Ill., assignors to (Cardox Corporation, Chicago, ill., a corporation of illinois Application June 8, 194%, Serial No. 31,736

ai claims.

, This invention relates to a method oi and apparatus` for the vaporization of carbon dioxide or other liqueiiable gases from a liquid phase, and the delivery of the vaporized gas at a ref'atively constant lov]v temperature to a point oi use or consumption.

When a large amount of carbon `dioxide vapor is required, such as for inerting storage tanks or: vessels'r containing inflammable vapor, it has been found to. be desirablev that the temperature of thevapor be kept at a relatively constant low value. .These conditions, when present, sat'sfy two veryA important requirements. A constant temperature isvery important'if not absolutely essential to the accurate determination and regulation of theV rate ofY discharge ofthe carbon dioxide vapor. Further, at low temperatures the density oi the discharged' vapor is greatest, and the discharge may be directed winto an atmosphere of relatively high density with less danger oi the vapor escaping through a top opening or hatch.

Another important remurementl for carbon dioxide vaporizers is that the liquid' carbon dioxide be completely vaporized before d'scharge. This feature is particularly essential in those cases Where the pressure of the vapor may he reduced to below 60 pound-s per square inch gauge as slugs or drops of liquid carbon dioxide would flash. to solid carbon dioxidewhich might result in pluggng of valves and conduits of the I unit. Complete vaporization oi the carbon dioxide canr be assured by heating the carbon dioxide to a temperature well above its vaporization temperature, but at this temperature the advantage oi the greater density at lower temperatures is lost.

Prior types.' oi carbon dioxide vaporizers have made poss'ble the enjoyment ofthe advanta'fes gained. by a low temperature discharge, or the advantage oi" complete vapori-ration; but it has not in the past been possible to realize both these advantages simultaneously. nor has it been possible to closely limit the variationsinvthe'dischargey temperature resulting from the lag inherent inmost temperaturecontrol devices.

It is then a primary objectfof this invention to. provide a direct draw carbon dioxide vaporizer capable of delivering a large quantity of carbon dioxide vapor at a relatively constant low temperature.

A further object of the invention is the prov'sion of a; novel. method and apparatus for the coinpete vaporization oi liqueiiable gases and thel delivery of the vaporized gases at a rela'ufely constant low temperature.

( Gl. (i2-l) A furtherobject of the invention is-to provide a method and apparatus for vaporizing` liquid carbon dioxide for delivery at a relatively constant and determinable rate oi iioiv.

A further object of the inventionis to provide a method -for completely vaporizing liquid carbon dioxide at a temperature Well above its vaporization temperature and delivering the carbon dioxide vapor to its point of use at a temperature near its vaporization temperature Without recomrnunication of the vapor with the liquid carbon dioxide.

A still further object of the invention is to provide a carbon dioxide vaporizer` having temperature responsive controls for the source` of heat and the vapor discharge, adapted to respond in accordance With the temperature of the vapor inside the vaporizing un-'t to control the application of heat regardless of Whether or not vapor is being withdrawn.

Other objects andadvantages of the `invention will become apparent during the course of the following description.

In the accompanying drawings forminga part of this specication and'in which like numerals are employed to designate like parts throughout the same,

Figure l is a vertical sectional View of a complete vaporizer unit illustrating an embodiment of the invention,

Figure 2 is a fragmentary, enlarged sectional view on l'ne 2 2 of Fig. 1,

Figure 3 is a fra'rrnentary, enlarged sectional View on ine 3 3 of Fig. 1,

Figure 4 is a vertical sectional view of a complete vaporizer unit illustrating a modification of the unit illustrated in Fig. 1,

Figure 5 is a vertical sectional view of the control switches illustrated in Figs. 1 and 4 on an enlarged scale, and

Figure 6 is a sectionalview on line 6-5 of Fig. 5.

ln the drawings, wherein for the purpose of illustraton, are shownthe preferred embodiments of this invention, and referring rst to Fig. 1, the nii-moral l designates a housing having openings 3 around its iov-fer portion for the admission of air and a stack 9 for the exhaust of combustion gases. The upper portion of theV side wall la. of the housing is surrounded by an encased layer of suitable heat insulating material li! and the top Wall 'lb oi the housing is provided with a lifting lug i i.

A gas burner I2 is positioned in the lower; portion of the Ahousing l and is so arranged that the heat therefrom Vwill rise upwardly through the center portion thereof. Attached to the gas burner l2 near the point of issuance of the flame from the burner tip 62a is a pilot burner IS. The gas burner l2 is supplied with fuel through a conduit lil having an electrically controlled shut-oi valve l5 and an automatic pressure regulator IS. The pilot burner I3 receives its supply of fuel through the conduit Il, having a manual shut-od valve i8, and is connected to the conduit l@ at i9.

The housing 'l is provided with a plurality of arms and a ring glia for supporting a Vaporizing coil 2l which has its inlet end portion Ela extending from the upper end of the coil and its outlet 2 lo at the lowervend of the coil. rI'he outlet 2lb is connected to a vertical pille 22 which passes upwardly through the bore of the Vaporizing coil El and through the top wall of the housing l. The inlet end portion 2 la of the vaporizing coil passes through the side wall la of the housing at a point somewhat below the upper end oi the vaporizing coil 2 l.

The several uppermost turns of the vaporicing coil 2l are spaced from each other by the bolts 24 which pass therebetween and through the straps 25 and 25'. The remaining turns of the vaporizing coil 2! form an unbroken surface by being placed in contact with each other. As a result of this arrangement, the hot gases rising from the burner tip lita must pass upwardly through the central bore of the vaporizing coil 2l, through the spaces provided between the uppermost turns of the coil, and then downwardly through the annular space formed between the wall la of the housing and the outer face of the vaporizing coil 2! to be finally exhausted from the housing 'l through the stack 9.

A cover plate 25 lies across the top of the vaporizing coil 2| and supports a double layer of r fire-brick 2l. The space between the lire-brick 2l and the top wall lb of the housing is filled with a suitable heat insulating material 23.

A heat exchange coil 29 surrounds the housing l and its encased heat insulating material lli near the medial portion of the housing. rlhis heat exchange coil is composed of an inner pipe 33 with an outer pipe 3l ccncentrically arranged therewith. This arrangement provides for the flow of uids through both of these pipes without communication therebetween. The inlet end 28a of the vaporizing coil is connected to the upper end of the inner pipe 3Q so as to provide communication between the heat exchange coil 2S and the vaporizing coil ai as illustrated in Fig. 2. The upper end of the vertical pipe 22 is connected to the upper end of the outer pipe 3l of the heat exchange coil E@ by the conduit 32. This arrangement places the outlet 2lb of the vaporizing coil 2i in communication with the outer pipe Se of the heat exchange coil 29. ii.

lower ends of the inner pipe 33 and the outer pipe 3i are separated at the lower end of the heat exchange coil 2S, as illustrated in Fig. 3. The lowe end Sta or" the inner pipe t is adapted to be connected to a source of supply of liquid carbon dioxide, not shown. The lower end of the outer pipe 3l is connected to the carbon dioxide vapor discharge con-duit that is provided with an electrically controlled shut-olf valve gli.

A bi--metal thermostat rod 35 is positioned within the vertical pipe 22 so that expansion and contraction of the rod will operate the microswitches and 3'? which in turn open or close the electric circuits which operate the electrically controlled valves l5 and 34. Reference character 38 designates a standard type of safety control switch not shown in detail. The switch is cf the type that is manually closed and is held in a closed position by the energization of a solenoid. The solenoid operates in response to current generated by Vthe thermocouple 38a and carried by the wires 32h so that1 if for any reason the pilot burner I3 is extinguished, the safety control switch 38 will open to cause the electrically ccntrolled valve I5 to be closed.

The electric circuit connecting the microswitch 35, the safety control switch 33, and the electrically controlled shut-off valve l5 in series across the power supply source consists of the wire c leading from the power source to the terminal on one side oi the microswitch 35, the wire d leading from one of the double-throw terminals on the other side of the microswitch 36 to one terminal of the safety control switch 38, the wire e leading from the other terminal of the safety control switch 3S to one terminal of the electrically controlled shut-off valve I5, and the wire f connecting the other terminal of the electrically controlled shut-olf valve l5 to the power source.

The electric circuit connecting the microswitch 3l and the electrically controlled shut-off valve Sil in series across the power source consists of the wire g connecting one terminal of the microswitch 3l to the power source, the wire h connecting a double-throw terminal on the opposite side of the microswitch 3l to one terminal of the electrically controlled shut-off valve 34, and the wire i connecting the other terminal of the valve 34 to the power source.

Referring now to Figs. 5 and 6 for a detailed description of the arrangement and operation of the microswitches 36 and 3l, the bi-metal rod 35 is composed of an outer tubular member 39 and an inner solid member All. These two members are connected at their lower extremities by a welded joint el. The outer member 39 is welded to the lower surface of the plug l2 at 43, and the upper end portion of the inner member 4i! passes through the plug 62 and proiects beyond the upper surface thereof for vertical movement in response to changes in the length of the outer member 3S. The proiecting portion of the inner member S3 is provided with a contact plate et which is rigidly connected thereto. The microswitches 35 and 3l are of standard construction and are of the single-pole, doublethrow, snap-action type disclosed in the P. K. MCC-fall patent, No. 1,960,020, issued 22, 1934. The microswitch Sil is rigidly mounted on the plate l5 by the pins l5 and el, and the microswitch 35 is similarly mounted on the plate i8 by two pins 4Q, only one of which is illustrated. The plate i5 and its attached microswitch 3l are in turn pivotally mounted on the supporting frame 5l by the pin fil, and the plate 58 and its attached microswitch Se are pivotally mounted on the supporting frame 52 by the pin 4S. A bracket 53 is connected to the upper portions of the two supporting frames di and 52 and supports the adjusting screws 5&5 and 55 which pass through the springs 56 to be threadedly connected to the lugs 5l and 58 which are mounted on the plates 45 and e3, respectively. The entire dual microswitch assembly is enclosed by a housing 5S having a detachable cover 53.

In operation, the outer member 3Q of the bimetal rod 35 responds to temperature changes by expanding and contracting. These expansions and contractions cause the inner member '40 to move the contact plate 44 up or down a corresponding distance. The depressible pins 6| ofthe microsvrit'che's 36 and 31 are located at points spacedonly short distances from the pivot pins 41 and 491 and respond to the movements of the contact plate 44 to open or close the circuitsthrough the microswitches 35 and 31, as the casel may be.

Only one of the double-throw terminals of each microsvvitch 36 and 31 is connectedin the electric circuit thereof, so that when the movable element of the switch is not engaging the connected terminal, the circuit is open. With this' arrangement, it is possible to connect the Wire h to one ofthe double-throw terminals of the microswitch 31 and the Wire d to the opposite double-throw terminal of the microsvvitcli 36 so that an upward movement of the contact plate M., depressing the pins 6|, will cause the circuit through the microsvvitch 31 to open and the circuit through the microswitch 36 to close. Thus, movement of the Contact plate 44 in an upward direction serves to close the electrically7 controlled shut-ofi valve' 34 and to open the electrically controlled shut-off valve l5'. Conversely, a down- Ward movement of the contact plate M. serves to reverse the above procedure to open the Valve 34 and to close the valve I5.

The points at which the microsivitches .5E and 31 Willl be caused to function to open or close their respectiver circuits may be individually adjusted by turning the adjusting screws and 55. This adjustment causes the plates lle and 45 to pivot about the pins l1 and 49 respectively, and thereby changes the positions of depressible pins 6| relative to the positions of the contact plate 44'. The setting and adjustment of the switches 36` and 31 will be further discussed in a later paragraph.

Referring now to Fig. 4' wherein is illustrated a modification of the embodiment or the invention illustrated in Fig. lc, the numeral @E designates a housing mounted on the supporting legs 55 and surrounded' by an encased layer oi suitable heat insulating material 61. The baile plates 53 are so'arranged Within'l the housing as to provide a tortuous path for the hot combustion' gases risingr therethrough to be exhausted through the stack 69.

The gas burner 1B, having a burner tip 1 ila'. is positioned beneath the central portion of the open bottom of the housing and supplied with fuel through the conduit 12 having an automatic pressure regulator 13 and an electrically controlled shut-off valve 14. The pilot hurner 1| for the burner 'it' is'supplied with fuel through. the conduit 15 having a manual shut-oil` valve 'i5 and' connected to the conduit 12 at A1vaporizing coil 1'! is suitably mounted' in the housing 55 and is so arranged' that the baille platesv 58' will' cause the heated'eases rising from theburri'er 1d to pass between its spaced turns. The inlet end 18 of the vaporizing coil pa es' through the side vvallV of' the hor-sing at a point near its' upper end' the outlet end ll'c is 'nected to a vertical pipe 19 which rises through thev bore of the vaporizing coil 1l and through the top Wall of the housing (i5.

A heat exchange coiled, surrounding the upper portion of the housing 65, is'cornposed of an'inner pipe 8| and: an outer pipe E2 con-centricarlly arranged one Within the other. Theinlet end 13 of the vanorizin'g coil is connected to the upper end' ofthe innerV pipe 5|-, andthe pipe e3 con-i nects the upper endof thevertical pipe 19 to the upper end of the cuter pipe 32, rlhe inner pipe 8| and the outer pipe 82 are separated at the lower end of the heat exchange coil d@ and the lower end 31a of the inner pipe Si is adapted to 'ce connected to a 'source of supply of liquid carbon dioxide, not shown. The lower end oi the outer pipe 82 is connected to the carbon dioxide vapor discharge conduit t; which is provided with an electrically controlled shut-oli valve 85.

The microswitches Sli and 37E used in conjunction with the device illustrated in Fig. 4 are identical to those illustrated in Figs. l, 5 and 6, and are similarly arranged. For this reason, the reierence characters designating them and the immediately associated parts will be consistent with those ofthe above mentioned figures.

The electric circuit connecting the microswitch Se, the safety control switch Sie, and the electrically controlled shutoil 'valve 'lll in series across the power supply source consists or" the wire y' leading fromv the power source te the terminal on one side of the microsvvitch 3S, the wire lc leading from one 01" the terminals on the other side oi the microswitch 355i to one side o1 the safety control switch Sli, the Wire Z leading from the other side of the safety control switch S9 to one terminal of the electrically controlled shutoff valve lll, and the wire m connecting the other terminal oi the electrically controlled shut-off valve lll to the power source.

The electric circuit connecting the microswitoh 31 and the electrically controlled shut-01T valve 85 in series across the pov/'er supply source consists 'of the Wire n connecting one terminal 0i the micrcswitch 3l to the power source, the Wire o connecting one of the double-throw terminal-s en ythe opposite side of the inicroswitch 31 to one terminal of the electrically controlled Shut-01T valve and the wire p connecting the other terminal of the valve 85 to the power source.

A bi-metal" thermostat rod 35 is positioned Within the vertical pip@ 1Q for operating the micrcswitches 3'? and 31 to open or close the electric cir-cuits vhich in turn operate the electrically controlled shut-ot? valves lll- 35. Reference character ce designates a control switch of a standard type which not shown in detail. The switch located the circuit for operating the valve 'it which controls the supply of fuel to the gas burner lil, and is of type that is `manually closed and is held a closed position by the energization of a sole-cid. solenoid is operatedv ip response to cui' g nerated by the thermocouple 89a and carr Vd the wires ib so that, if for reason the pilot burner 'il is extinguished, the safety control switch will open causing the electrically controlled valve 14 to be closed.

ewan-rement and operation oF the microswitches and 31 illustrated in Fig. 4*, being identical to that illustrated in Figs. l, 6,

redescrihed at this point.

. ig once again to Fig. l for a descriphe operation of the vacorizer therein illustrated.' the liouid carbon diofrom its source' of supply, not fn, enters the eat erchange coil 2S indicated hy the arr at From th' point of entrance. the liquid carhon dioxidel pases throngh the inner pipe of the heatexchan-"fe coil 29 and to the inlet end portion 2 la of the varmiring"coilA 2 i. The carbon dic/ride then sses through. the vaporieing'coil 2l Where it is completely vapori'red by the heatsupplied by theiburner l2'. rhe carbon dioxide vapor thus formed then passes through the outlet 2 Ib of the vaporizing coil and enters the vertical pipe 22 where it passes in contact with the bi-metal thermostat rod 35 to enter the conduit 32. rIhis conduit directs the heated vapor into the outer pipe 3l of the heat exchange coil 29 where it is in heat exchange relationship with the inner pipe 30. The heated vapor is thus cooled during its passage through the outer pipe 3l by its contact with the inner pipe 33, which contains the liquid carbon dioxide, and leaves the heat exchange coil 29 to enter the carbon dioxide vapor discharge conduit 33.

The contact of the carbon dioxide vapor with the bi-metal thermostat rod 35 in the pipe 22 causes the rod to respond to temperature changes of the carbon dioxide vapor leaving the Vaporizing coil 2l through the pipe 22. When the temperature oi' the vapor drops, the bi-metal rod 35 contracts causing the microswitch 36 to function to close its electric circuit and open the valve l in the fuel supply conduit Hi whereby the gas burner i2 is ignited and the heat therefrom causes the temperature of the carbon dioxide vapor passing through the vaporizing coil 2l and the pipe 22 to rise. is the vapor temperature rises the bi-rnetal rod expands causing the microswitch 35 to function to open its electric circuit which closes the electrically controlled shut-oil valve hl whereby the supply of fuel to the burner l2 is cut oi. The pilot burner i3 serves to automatically ignite the gas burner i2 when it is again supplied with fuel. The safety control switch 3B functions to prevent opening of the electric control valve i5 if for any reason the pilot burner i3 is extinguished whereby the fuel supplied to the burner i2 could not be ignited and would escape creating the possibility of an explosion.

The microswitch 3l responds to the action of the loi-rnetal rod 35 in a manner similar t0 that of the microswitch Se. However, the temperature ci the carbon dioxide vapor at which the microswitches and 3l react may be varied individually. The adjustment of the microswitch 3l is such that the electric circuit through the same and the electrically controlled valve 3@ is actuated only when contraction of the bi-metal rod 35 is beyond the normal operating range and the temperature of the carbon dioxide vapor is below the desired minimum temperature. In this oase, the eleotrically controlled valve 34 closes to prevent passage of +he carbon dioxide vapor from vaporizer. As a result of this action it is possible to arrange the adjustment of the microswitch Si' so that it is impossible for incompletely vaporized carbo-n dioxide to escape from the vaporizing device.

The operation of the modification illustrated in ll is similar to that of the device illustrated in Fig. l and will not be again described.

Adjustment of the microswitches 35 and 3l as to the temperatures at which they will function will oi course vary with the different requirements er ountered. The temperature and pressure conditions of the liquid carbon dioxide in the source of supply employed and the temperature and pressure requirement for the discharged carbon dioxide vapor will vary from time to time. With these variables in mind and with no intent to limit the scope oi the invention, as claimed, a typical set of operating conditions will be described in the following example.

Having a supply of liquid carbon dioxide, not shown, stored at a temperature of 0 F. and a pressure of 305 pounds per square inch, absolute, the microswitch 3G may be set to cause the electrically controlled shut-off valve l5 to open when the temperature of the carbon dioxide vapor in the pipe 22 drops below 210 F., and to close when the temperature of the vapor in the pipe 22 exceeds 210 F. The microswitch 3l will be set to function to cause the electrically controlled valve 34 to close when the temperature of the carbon dioxide Vapor in the pipe 22 drops below 70 F. It will be noted that under normal operating conditions, the valve 34 will remain open at all times.

The liquid carbon dioxide from the source of supply, not shown, enters the vaporizer through the heat exchange coil 29 at A, and in passing therethrough and into the vaporizing coil 2l suers a small pressure drop due to the pipe friction. As the carbon dioxide then continues through the vaporizing coil 2l the pressure continues to drop due to the pipe friction and the carbon dioxide absorbs heat supplied by the hot combustion gases from the burner l2 until it is completely Vaporized. This complete vaporization will be accomplished at some point below a temperature of 87.8 F. which is the critical temperature for carbon dioxide. After the complete vaporization of the carbon dioxide, the vapor continues to absorb heat until it reaches a temperature of 210 F., the temperature corresponding to the setting of the microswitoh 3S, at which time the shut-oile valve I5 will close to prevent a further increase in the temperature of the vapor. The heated carbon dioxide vapor passes from the vaporizing coil 2l' through the vertical pipe 22 and the conduit 32 into the heat exchange coil 29. At this point the temperature oi the carbo-n dioxide-v vapor will be 210 F. and it will be at a pressure of approximately 205 pounds per square inch, absolute,

Due to the fact that the heat retaining capacity of the carbon dioxide vapor is Very low, the vapor during its passage through the heat exchange coil 29 will drop in temperature to approximately 30 F. and its pressure upon leaving the heat exchange coil 29 will be approximately 185 pounds per square inch, absolute. Due to the large temperature drop in the carbon dioxide vapor as it passes through the heat exchange coil 29, and to the fact that the carbon dioxide vapor has a low heat retaining capacity, any differences in the carbon dioxide temperature as it leaves the vaporizing coil 2| will be reduced to an insignificant amount before the vapor is discharged from. the heat exchange coil 2S into the conduit The pressure drop of the carbon dioxide vapor through conduit 3S to the point of delivery may be varied according to the requirements of the use to which the carbon dioxide vapor is to be put.

It is to be understood that the forms of this invention, herewith shown and described, are to be taken as preferred examples of the same, and that various changes in the shape, size and` arrangement of parts ma?.7 be resorted to, without departing from the spirit of the invention, or the scope of the subjoined claims.

Having thus described our invention, we claim:

1. Apparatus for vaporizing liquid carbon dioxide comprising, a heat exchanger in communication with aV liquid carbon dioxide supply source, a coil adapted to receive liquid carbon dioxide from said heat exchanger, automatically controlled means for supplying heat to said coil to vaporize said liquid carbon dioxide, means for passing the vaporized carbon dioxide from said coil through said heat exchanger, and automatic valve means responsive to changes in the `9 temperature of the carbon dioxide vapor passing, from said coil for controlling the passage of carbon dioxide vapor from said heat exchanger.

2. Apparatus for vaporizing liquid carbon dioxide comprising, a heat exchanger in communication with a liquid carbon dioxide supply source, a coil adapted to receive liquid carbon dioxide from said heat exchanger, automatically controlled means for supplying heat to said coil to vaporize the liquid carbon dioxide therein and' elevate the temperature of the carbon dioxide vapor to a given point considerably above its vaporization temperature, means for passing the heated carbon dioxide vapor from said coil through said heat exchanger to lower the temperature of said vapor, and an automatic Valve responsive to a reduction in the' temperature of the carbon dioxide vapor passing from said coil to a point below said given point for preventing the passage of carbon dioxide vapor from said heat exchanger.

3. Apparatus for vaporizing liquid' carbon dioxideV comprising, a heat exchange device adapted toreceive liquid carbon dioxide from a storage receptacle, a heating coil having an inlet and an outlet and adapted to receive carbon dioxide vapor and liquid from said heat exchange device, automatically controlled means responsive to the temperature of the carbon dioxide vat the outlet of said coil for supplying only suicient heat to said coil to completely vaporize the liquid carbon dioxide and elevate the temperature of the carbon dioxide vapor to a given point-above `its vaporization temperature, and discharge means for withdrawing the heated vapor from said coil through said heat exchange device to cool the vapor and supply heat to the associated liquid carbon dioxide to partially vaporize the same.

4. Apparatus for vaporizing liquid carbon dioxide comprising, an indirect heat exchange device adapted to receive liquid carbon dioxide from a storage receptacle, a heating coil connectedcto said heat exchange device to receive the carbon dioxide vapor and liquid passing therethrough, means for supplying heat to said heating coil to completely vaporize the liquid carbon dioxide and elevate the temperature of the carbon dioxide vapor to a point above its critical temperature, means for automatically regulating said heat supplying means, and discharge means for withdrawing the heated'vapor fromwsaidcoilv through said heat exchange de- Vice' to'.l cool the vapor and supply heat to the associated liquid carbon dioxideV to partially vaporize the same.

5. Apparatus for vaporizing liquid carbon dioxide comprising, an indirect heat exchange device` adapted to receive liquid carbon dioxide from a supply container, a heating coil connected to said heat exchange device to receive the carbon dioxide Vapor and liquid passing therethrough, means for supplying heat to said heating coil to vaporize the liquid carbon dioxide, temperature responsive control means for said heat supplying means, discharge means for withdrawing the vapor-ized carbon dioxide from said coil through said heat exchange device, and automatic valve means responsive to the temperature of the carbon dioxide passing from saidicoil for'controlling the discharge of carbon dioxide` vapor from said discharge means.

6. Apparatus for vaporizing liquid carbon dioxide comprising, an indirect heat exchange exchange coil, the said tubes at the lower end 10 device, a heating coil adapted to receive liquid carbon dioxide from a storage receptacle through said heat exchange device, means for supplying heat to said heating coil. to vaporize said liquid carbon dioxide and raise the temperature of the carbon dioxide vapor to a point above its critical temperature, temperature responsive means for controiling said heat supplying means to maintain a relatively constant vapor temperature in said coil, and discharge means for withdrawing the carbon dioxide vapor from said coil through said heat exchange device t0 lower the temperature of said vapor and decrease the slight temperature differentials due to l fluctuation in the temperature responsive means.

7. A device of the type described comprising, a cylindrical heating chamber, a base for mounting said chamber in an axially Vertical position, a heating coil positioned coaxially within said chamber havingl an inlet at the upper end portion and an outlet at the lower end portion of said chamber, means for supplying heat to the lower end portion of said chamber, a concentric tube heat exchange coil closely surrounding said chamber, means connecting the inlet of said heating Acoil to one of the concentric tubes at the upper end portion of said heat exchange coil, and'means connecting the outlet of said heating coil to the other concentric tube at the upper end portion of said heat portion of said heat exchange coil being separated to form an inlet and outlet for the interconnected heating and heat exchange coils.

8, A device oi the type described comprising, a cylindrical heating chamber, a base for mounting said chamber in an axially vertical position, a heating coil positioned coaxially within said chamber having an inlet at the upper end portion and an outlet at the lower end portion of said chamber, means for supplying heat to the lower end portionl of said chamber, a concentric tube heat exchange coil closely surrounding said chamber, means connecting the inlet of said heating coil to theinner concentric tube at the upper end portion of said heat exchange coil,v

means connecting the outlet of said heating coil to the outer concentric tube at the upper end portion of said heat exchange coil through a vertical tube within said chamber, the said tubes at the lower end portion of said heat exchange coil being separatedl to form an inlet and outlet for the interconnected heating and heat exchange coils, valve means for opening and closing said inlet, and valve means for openingl and closing said outlet.

9. A device oi the type described comprising, a cylindrical heating chamber, a base for mounting said chamber in an axially vertical position, a heating coil positioned coaxially within said chamber having an inlet at the upper end portion and an outlet at' the lower end portion of said chamber, meansfor supplying heat to the lower end portion of said chamber, a concentric tube heat exchange coil closely surrounding said chamber, means connecting the inlet of said heating coil tothe inner concentric tube at the upper end portion of said heat exchange coil, means connecting the outlet of said heating coil to the outer concentric tube at the upper end portion of said heat exchange coil through av vertical tube within said chamber, the saidl tubes at the lower end portion of said heat exchange coil being separated to form an inlet and outlet 4ior the interconnected heating and heat ex- 'il change coils, valve means for opening and closing said inlet, valve means for opening and closing said outlet, and automatic means for controlling said outlet valve means and said heat supplying means.

1U. A device of the type described comprising, a cylindrical heating chamber, a base for mounting said chamber in an axially vertical position, a heating coil positioned coaxially within said chamber having an inlet at the upper end portion and an outlet at the lower end portion oi' said chamber, means for supplying heat to the lower end portion of said chamber, a concentric tube heat exchange coil closely surrounding said chamber, means connecting the inlet of said heating coil to the inner concentric tube at the upper end portion of said heat exchange coil, means connecting the outlet oi said heating coil to the outer concentric tube at the upper end portion o1 said heat exchange coil through a vertical tube within said chamber, the said tubes at the lower end portion of said heat exchange coil being separated to form an inlet and outlet for the interconnected heating and heat exchange coils, valve means for opening and closing said inlet, valve means for opening and closing said outlet, and temperature responsive automatic means associated with said vertical tube to control said outlet valve means and said heat supplying means.

1l. A device of the type described comprising, a cylindrical heating chamber, a base for mounting said chamber in an axially vertical position, a heating coil positioned coaxially within said chamber having an inlet at the upper end portion and an outlet at the lower end portion of said chamber, means for supplying heat to the lower end portion of said chamber, a concentric tube heat exchange coil closely surrounding said chamber, means connecting the inlet oi said heating coil to the inner concentric tube at the upper end portion oi said heat exchange coil, means connecting the outlet of said heating coil to the outer concentric tube at the upper end portion of said heat exchange coil through a vertical tube within said chamber, the said tubes at the lower end portion of said heat exchange coil being separated to form an inlet and outlet for the interconnected heating and heat exchange coils, valve means for opening and closing said inlet, valve means for opening and closing said outlet, and a bi-metal thermostat within said vertical tube adapted to automatically operate said outlet valve means and control said heat supply means.

12. A method of vaporizing liquid carbon dioxide comprising, withdrawing liquid carbon dioxide froin a source of supply at approximately 1T'. and its corresponding Vapor pressure, heating the withdrawn carbon dioxide to a temperature above its critical temperature to completely vaporize the same and to raise the temperature of the carbon dioxide vapor, passing the heated carbon dioxide vapor in indirect heat exchange relationship with the withdrawn liquid carbon dioxide to partially vaporize the same and to lower the temperature of the carbon dioxide vapor to a point below that of the atmosphere into which it is to be discharged, and delivering the cooled carbon dioxide to its intended point of discharge.

13. A method of Vaporizing liquid carbon dioxide comprising, withdrawing liquid carbon dioxide from a source of supply, heating the Withdrawn liquid carbon dioxide to partially vaporize the same, heating the resulting carbon dioxide Vapor and liquid to a temperature above the critical temperature thereof to completely vaporize said liquid and to elevate the tempera'-A ture of said vapor, controlling ythe heat applied to said carbon dioxide vapor and liquid in response to the temperature oi the heated vapor, passing said seated vapor in indirect heat exchange relationship with said withdrawn liquid to lower the temperature of said Vapor to approximately 30 F. and to heat said withdrawn liquid to bring about the aforementioned partial vaporization oi the same, and delivering the cooled carbon dioxide vapor to its intended place of use.

14. A method of vaporizing liquid carbon dioxide comprising, withdrawing liquid carbon dioxide from a source of supply, heating the withdrawn carbon dioxide to vaporize the same and raise the temperature of the resulting vapor to a predetermined value substantially above its critical temperature, stopping the application of heat to the carbon dioxide when the vapor temperature exceeds said predetermined value, resuming the application of heat to the carbon dioxide when the vapor temperature falls below said predetermined value, passing the heated carbon dioxide vapor in indirect heat exchange relationship with said withdrawn liquid to lower the temperature of said vapor to approximately 38 F. and partially vaporiae said withdrawn liquid, and delivering the cooled carbon dioxide vapor to its intended place or" use.

15. A method of vaporizing liquid carbon dioxide comprising, withdrawing liquid carbon dioxide from a source of supply, heating the with- Y drawn liquid carbon dioxide to completely vaporize the same and to raise the temperature of resulting vapor to approximately 200 F., controlling the heat applied to said withdrawn carbon dioxide in response to changes in the temperature o1" said vapor, passing said heated rapor in indirect heat exchange relationship withI` said withdrawn liquid to lower the temperature of said vapor to approximately 30 F., delivering the cooled carbon dioxide vapor to its intended-' place of use, and stopping the delivery of said cooled carbon dioxide vapor when the temperature of said heated Vapor Yfalls below its critical"` temperature.

i6. A method of vaporizing liquid carbon di-. oxide comprising, delivering liquid carbon dioxide; to a coniined flow path, heating the carbon dioxide iiowing through said path to completely vaporize the same and to superheat the resultant vapor to a temperature sufiiciently above its vaporization temperature to prevent reliquefying of any oi said Vapor during the iollowing heat eX- changing step, varying the application of heat to said iiowing carbon dioxide in accordance with variations of the temperature ci said superheated vapor before the following heat exchanging step, passing the super-heated carbon dioxide vapor in indirect heat exchange relationship with the liquid carbon dioxide being delivered to lower the temperature of the Vapor, and discharging the cooled carbon dioxide vapor to a point of use.

1'?. A method of vaporizing liquid carbon dioxide comprising, delivering liquid carbon dioxide to a conned ow path, heating the carbon dioxide iiowing through said path to completely vaporize the same and to superheat the resultant vapor to a temperature sufficiently above its vaporization temperature to prevent reliquefying of any of said vapor during the following heat exchanging step, passing the superheated carbon dioxide vapor in indirect heat exchange relationship with the liquid carbon dioxide being delivered to lower the temperature of the vapor, and discharging the cooled carbon dioxide vapor to a point of use only when the temperature of the superheated vapor exceeds a given value.

18. A method of vaporizing liquid carbon dioxide comprising, delivering liquid carbon dioxide to a confined ow path, heating the carbon dioxide flowing through said path to completely vaporize the same and to superheat the resultant vapor to a temperature suiiiciently above its vaporization temperature to prevent reliquefying of any of said vapor during the following heat exchanging step, varying the application of heat to said flowing carbon dioxide in accordance with Variations of the temperature of said superheated vapor before the following l heat exchanging step, passing the superheated carbon dioxide vapor in indirect heat exchange relationship with the liquid carbon dioxide being delivered to lower the temperature of the vapor, and discharging the cooled carbon dioxide vapor to a point of use for so long as the temperature of the superheated vapor remains above a given value.

19. A method of vaporizing liquid carbon dioxide comprising, delivering liquid carbon dioxide to a coniined flow path, heating the carbon dioxide flowing through said path to completely vaporize the same and to superheat the resultant vapor to a temperature sufliciently above its vaporization temperature to prevent reliquefying of any of the vapor during the following heat exchanging step, varying the application of heat to said flowing carbon dioxide in accordance with variations yof the temperature of said superheated vapor before the following heat exchanging step, passing the superheated carbon dioxide vapor in indirect heat exchange relationship with the liquid carbon dioxide being delivered to lower the temperature of the vapor` and to apply the heat thus extracted from the vapor to the liquid being delivered, and discharging the cooled carbon dioxide vapor at a substantially uniform low temperature to a point of use.

20. Apparatus for vaporizing liquid carbon dioxide comprising, a heat exchanger adapted to receive liquid carbon dioxide from a supply source, heating means in communication with said heat exchanger for receiving liquid carbon dioxide from the heat exchanger, means for supplying heat to said heating means, automatic means responsive to the temperature of the carbon dioxide at the discharge of the heating means for controlling the amount of heat supplied to said heating means to completely vaporize the liquid carbon dioxide and elevate the temperature of the resultant vapor to a point above its vaporization temperature, and means for passing the heated carbon dioxide vapor from said heating means through said heat exchanger to lower the temperature of said vapor and partially vaporize the associated liquid carbon dioxide.

21. Apparatus for vaporizing liquid carbon dioxide comprising, a heat exchanger adapted to receive liquid carbon dioxide from a supply source, heating means in communication with said heat exchanger for receiving liquid carbon dioxide from the heat exchanger, means for applying heat to said heating means, automatic means responsive to the temperature of the carbon dioxide at the discharge of the heating means for controlling the amount of heat supplied to said heating means to eiTect complete vaporization of the liquid carbon dioxide therein, means for passing the vaporized carbon dioxide from said heating means through said heat exchanger, and automatically acting means for effecting discharge of carbon dioxide vapor from said heat exchanger only when the temperature of the carbon dioxide at the discharge of the heating means exceeds a given value.

HILDING V. WILLIAMSON. JAMES C. HESSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,859,442 Henderson May 24, 1932 1,905,971 Davisson et al Apr. 25, 1933 2,034,693 Datin Mar. 24, 1936 2,062,827 Ruppricht Dec. 1, 1936 2,273,257 Gardner Feb. 17, 1942 2,343,727 Zenner Mar. 7, 1944 2,352,775 Dittmer July 4, 1944 2,361,252 Welch Oct. 24, 1944 

1. APPARATUS FOR VAPORIZING LIQUID CARBON DIOXIDE COMPRISING, A HEAT EXCHANGER IN COMMUNICATION WITH A LIQUID CARBON DIOXIDE SUPPLY SOURCE, A COIL ADAPTED TO RECEIVE LIQUID CARBON DIOXIDE FROM SAID HEAT EXCHANGER, AUTOMATICALLY CONTROLLED MEANS FOR SUPPLYING HEAT TO SAID COIL TO VAPORIZE SAID LIQUID CARBON DIOXIDE, MEANS FOR PASSING THE VAPORIZED CARBON DIOXIDE FROM SAID COIL THROUGH SAID HEAT EXCHANGER, AND AUTOMATIC VALVE MEANS RESPONSIVE TO CHANGES IN THE TEMPERATURE OF THE CARBON DIOXIDE VAPOR PASSING FROM SAID COIL FOR CONTROLLING THE PASSAGE OF CARBON DIOXIDE VAPOR FROM SAID HEAT EXCHANGER.
 20. APPARATUS FOR VAPORIZING LIQUID CARBON DIOXIDE COMPRISING, A HEAT EXCHANGER ADAPTED TO RECEIVE LIQUID CARBON DIOXIDE FROM A SUPPLY SOURCE, HEATING MEANS IN COMMUNICATION WITH SAID HEAT EXCHANGER FOR RECEIVING LIQUID CARBON DIOXIDE FROM THE HEAT EXCHANGER, MEANS FOR SUPPLYING HEAT TO SAID HEATING MEANS, AUTOMATIC MEANS RESPONSIVE TO THE TEMPERATURE OF THE CARBON DIOXIDE AT THE DISCHARGE OF THE HEATING MEANS FOR CONTROLLING THE AMOUNT OF HEAT SUPPLIED TO SAID HEATING MEANS TO COMPLETELY VAPORIZE THE LIQUID CARBON DIOXIDE AND ELEVATE THE TEMPERATURE OF THE RESULTANT VAPOR TO A POINT ABOVE ITS VAPORIZING TEMPERATURE, AND MEANS FOR PASSING THE HEATED CARBON DIOXIDE VAPOR FROM SAID HEATING MEANS THROUGH SAID HEAT EXCHANGER TO LOWER THE TEMPERATURE OF SAID VAPOR AND PARTIALLY VAPORIZE THE ASSOCIATED LIQUID CARBON DIOXIDE. 